This proposal sets forth two related research projects designed to rigorously test several hypotheses that have important implications for fertility movements in the 1970's. We first propose two simultaneous- equations models that will test these hypotheses against alternative formulations suggested by recent exonomic theories of fertility and household behavior. The first model explains age-specidic fertility rates, marriage rates, and labor force participation rates by sex since World War II. This model will use the detailed annual demographic and economic data available through 1972 by age groups to investigate the behavior of young people, who are first and most affected by several important aspects of business cyclical relationships, and who are in prime fertility ages. The other model will use a set of annual, quinquiennial, and decennial data series extending back to the Civil War. Although age- specific detail will be lacking, these long-term data will enable examination within a unified conceptual and statistical frame-work of several related phenomena that have important consequences for the post- World War II period. The second project uses the substantial information on fluctuations in birth rates and completed fertility that exists in recent cross- sectional data sources. We will use appropriate regression analysis techniques to explore age-cohort differences in the relationships among completed fertility, timing and spacing of children, husbands' and wifes' wages and education, and family income. Three household-level data sets--the 1966-67 Survey of Economic Opportunity, the 1960 and 1970 Census Public Use Samples, and the 1965 National Fertility Survey--will be used in this analysis.